Liquid-crystal-on-silicon (LCoS) displays are used in consumer electronics, such as hand-held projectors and near-eye displays. FIG. 1 shows one exemplary use scenario for a prior art LCoS panel 200, wherein LCoS panel 200 is located on a PCB 102 incorporated into a near-eye display 130 attached to eyeglasses 120. LCoS panel 200 may alternately be employed in a different display device, such as in a hand-held image projector.
FIG. 2 is a perspective view of prior-art LCoS panel 200. LCoS panel 200 includes a cover glass 219 on a semiconductor wafer 214. A liquid crystal layer 217 is between cover glass 219 and semiconductor wafer 214. A pixel array 215 is between the liquid crystal layer 217 and semiconductor wafer 214. A corner portion of liquid crystal layer 217 is not shown to reveal pixel array 215 beneath it. Semiconductor wafer 214 has a bottom surface 214B and a top surface 214T. Top surface 214T includes a plurality of bond pads 287 that control each pixel of pixel array 215, as known in the art.
A transparent conductive layer 218 is on the surface of cover glass 219 adjacent to liquid crystal layer 217. For clarity of illustration, FIG. 2 shows only a portion of conductive layer 218 on overhang region 229 of cover glass 219. Dam 216 contains liquid crystal layer 217. Semiconductor wafer 214 is formed of silicon, for example. Transparent conductive layer 218 is deposited on cover glass 219, and is, for example, formed of indium titanium oxide (ITO). LCoS panel 200 has a panel width 222 and a panel depth 223.
FIG. 3 is a cross-sectional view of a prior-art mounted LCoS panel 300 that includes LCoS panel 200 electrically connected to a flexible printed circuit assembly (FPCA) 302. In FIG. 3, reference numerals between 200 and 300 denote parts of LCoS panel 200 introduced in FIG. 2. FPCA 302 includes a surface-mount connector (not shown) for mechanical and electrical connection to a printed circuit board. The portion of FPCA 302 shown in FIG. 2 is bonded to a rigid substrate 350, which is formed of metal, for example.
LCoS panel 200 is electrically connected to FPCA 302 via a plurality of wire bonds 383, conductive glue 386, and a soldering layer 388. Conductive glue 386 has a height 386H. Encapsulation glue 391 covers wire bonds 383. Soldering layer 388 and conductive glue 386 electrically connect transparent conductive layer 218 to a conductive pad 304 of FPCA 302, which is connected to a conductive pad trace 306 of FPCA 302. Each of a plurality of address electrodes 305 of FPCA 302 receives a signal from a respective one of a plurality of address electrode traces 303 of FPCA 302. Each wire bond 383 carries a signal from a respective address electrode 305 to a respective bond pad 287. Address electrodes 305, wire bonds 383, and bond pads 287 are arranged in respective one-dimensional arrays into the plane of FIG. 3 such that each address electrode 305 is substantially aligned with a respective bond pad 287.